1. Field
The invention is in the field of catheter devices of outside-the-needle type, as employed for supplying liquids intravenously.
2. State of the Art
Devices of the type concerned are well known and widely used for intravenous administration of various liquids, such as parenteral solutions, for blood transfusions, etc. Such devices may also be adapted in known manner to remove liquids from the body for a variety of purposes, such as for the making of medical laboratory tests.
As originally constructed, outside-the-needle catheter devices have suffered from messy blood spillage and contamination during the time the venipuncture needle has been withdrawn from the catheter or cannula immediately after placement of the catheter in a vein and before the venoclysis set has been connected to the catheter. This has been highly undesirable for a variety of reasons. Besides being unsanitary and inconvenient, it has tended to frighten the patient.
Subsequent designs utilizing a Y-formed (side-arm-provided) hub for the catheter, so the venoclysis set can be connected to one branch of the Y formation prior to venipuncture and subsequent withdrawal of the needle, have not eliminated the problems even though they have helped considerably. Following venipuncture, withdrawal of the needle from the puncture-hole through the rubber sealing cap that is provided on the other branch of the Y formation has resulted in messy and undesirable leakage of venoclysis liquid, usually mixed with the initial backflow blood, during administration of such liquid. The desired and expected automatic sealing of the cap following needle withdrawal does not normally work out in practice due to a tendency for the defining margins of the puncture-hole through the rubber or flexible plastic materials to acquire a "set" over usual shelf-life time periods, thus allowing leakage.